Experimental studies are designed to elucidate the molecular basis of the primary process of vision. Direct emphasis is given to the structural and functional role played by rhodopsin, the chromophoric protein photoreceptor. Upon the absorption of a photon the rhodopsin chromophore undergoes a sequence of conformational changes. Through the use of flash photolysis spectroscopy and ultra rapid kinetic techniques dynamic changes in protein structure and membrane environment of being correlated with the chromophore changes to construct a molecular picture of the transduction process. Picosecond studies of rhodopsin from various species and of rhodopsins with incorporated retinal analogs are being investigated to elucidate the first photo induced intermediate bathorhodopsin. On a slower timescale, microseconds-milliseconds, membrane environment and protein conformational changes are sought through the use of fluorescent probes. The experiments are designed to probe features of the chromophore site, features of protein structure and features of the membrane environment required by rhodopsin to function dynamically as a molecular trigger.